The fabrication and mechanical testing of thin CYTOP membranes is explored for implementation with surface plasmon waveguides. A membrane supported gold strip allows for the propagation of Long-Range Surface Plasmon Polaritons (LRSPPs) and functionality as a biochemical sensor. The fabrication of 25nm thick gold waveguides on thin (400nm) CYTOP membranes is described. Critical process steps include the CYTOP spin and curing procedure, metal lithography for forming the waveguides and wafer passivation during membrane release. Mechanical properties of the CYTOP membranes were experimentally determined through application of the bulge test. The extracted value for Young's Modulus was 1.4±0.2 GPa and residual film stress was 30.8±1.8 MPa. Narrow (200μm) membranes were observed to be able to withstand over 30kPa of differential pressure without failure.